Certified Rhythm Analysis Technician (CRAT) Practice Exam

The arrhythmia characterized by wide and bizarre QRS complexes is premature ventricular contractions (PVCs). PVCs occur when an electrical impulse originates in the ventricles instead of the atria, leading to a heartbeat that is different from the normal sinus rhythm. The QRS complex in PVCs is typically wider than normal because it bypasses the typical conduction pathway through the AV node and His-Purkinje system, leading to a slow and irregular depolarization of the ventricles.

This distinct morphology of the QRS complex is key in identifying PVCs, as the wide and bizarre appearance stands out compared to the normal narrower QRS complexes seen in other arrhythmias such as sinus tachycardia or first-degree AV block. PVCs often can be seen on an electrocardiogram (ECG) as isolated beats that interrupt the regular rhythm, which further aids in their recognition as distinct from other arrhythmias.

Ventricular fibrillation, while also involving the ventricles, is a chaotic and life-threatening rhythm that presents with no identifiable QRS complexes and is instead characterized by erratic electrical activity. Sinus tachycardia features narrow QRS complexes because the impulses originate from the atria and travel normally through the conduction